21072429 has 24 divisors (see below), whose sum is σ = 35448192. Its totient is φ = 11812320.

The previous prime is 21072421. The next prime is 21072431. The reversal of 21072429 is 92427012.

It is not a de Polignac number, because 21072429 - 2³ = 21072421 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21072421) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 184 + ... + 6494.

It is an arithmetic number, because the mean of its divisors is an integer number (1477008).

Almost surely, 2^21072429 is an apocalyptic number.

It is an amenable number.

21072429 is a deficient number, since it is larger than the sum of its proper divisors (14375763).

21072429 is a wasteful number, since it uses less digits than its factorization.

21072429 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6377 (or 6374 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21072429 is about 4590.4715444059. The cubic root of 21072429 is about 276.2092379951.

The spelling of 21072429 in words is "twenty-one million, seventy-two thousand, four hundred twenty-nine".