31100021 has 16 divisors (see below), whose sum is σ = 33929280. Its totient is φ = 28396800.

The previous prime is 31100011. The next prime is 31100023. The reversal of 31100021 is 12000113.

It is a de Polignac number, because none of the positive numbers 2^k-31100021 is a prime.

It is a super-2 number, since 2×31100021² = 1934422612400882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 31099981 and 31100008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31100023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 101150 + ... + 101456.

It is an arithmetic number, because the mean of its divisors is an integer number (2120580).

Almost surely, 2^31100021 is an apocalyptic number.

It is an amenable number.

31100021 is a deficient number, since it is larger than the sum of its proper divisors (2829259).

31100021 is a wasteful number, since it uses less digits than its factorization.

31100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484.

The product of its (nonzero) digits is 6, while the sum is 8.

The square root of 31100021 is about 5576.7392802605. The cubic root of 31100021 is about 314.4755563294.

Adding to 31100021 its reverse (12000113), we get a palindrome (43100134).

The spelling of 31100021 in words is "thirty-one million, one hundred thousand, twenty-one".