21021010 has 16 divisors (see below), whose sum is σ = 40063896. Its totient is φ = 7913728.

The previous prime is 21021001. The next prime is 21021043. The reversal of 21021010 is 1012012.

It can be written as a sum of positive squares in 4 ways, for example, as 20169081 + 851929 = 4491^2 + 923^2 .

It is a super-2 number, since 2×21021010² = 883765722840200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21020984 and 21021002.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61657 + ... + 61996.

Almost surely, 2^21021010 is an apocalyptic number.

21021010 is a deficient number, since it is larger than the sum of its proper divisors (19042886).

21021010 is a wasteful number, since it uses less digits than its factorization.

21021010 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123677.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21021010 is about 4584.8675008118. The cubic root of 21021010 is about 275.9843949029.

Adding to 21021010 its reverse (1012012), we get a palindrome (22033022).

The spelling of 21021010 in words is "twenty-one million, twenty-one thousand, ten".