21351929 has 4 divisors (see below), whose sum is σ = 21505680. Its totient is φ = 21198180.

The previous prime is 21351919. The next prime is 21351943. The reversal of 21351929 is 92915312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21351929 - 2¹⁶ = 21286393 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21351895 and 21351904.

It is not an unprimeable number, because it can be changed into a prime (21351919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76667 + ... + 76944.

It is an arithmetic number, because the mean of its divisors is an integer number (5376420).

Almost surely, 2^21351929 is an apocalyptic number.

It is an amenable number.

21351929 is a deficient number, since it is larger than the sum of its proper divisors (153751).

21351929 is a wasteful number, since it uses less digits than its factorization.

21351929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153750.

The product of its digits is 4860, while the sum is 32.

The square root of 21351929 is about 4620.8147549972. The cubic root of 21351929 is about 277.4250708068.

The spelling of 21351929 in words is "twenty-one million, three hundred fifty-one thousand, nine hundred twenty-nine".