21355929 has 24 divisors (see below), whose sum is σ = 35418240. Its totient is φ = 12146688.

The previous prime is 21355921. The next prime is 21355949. The reversal of 21355929 is 92955312.

It is a happy number.

It is not a de Polignac number, because 21355929 - 2³ = 21355921 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21355893 and 21355902.

It is not an unprimeable number, because it can be changed into a prime (21355921) 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, 15532 + ... + 16850.

It is an arithmetic number, because the mean of its divisors is an integer number (1475760).

Almost surely, 2^21355929 is an apocalyptic number.

It is an amenable number.

21355929 is a deficient number, since it is larger than the sum of its proper divisors (14062311).

21355929 is a wasteful number, since it uses less digits than its factorization.

21355929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1589 (or 1586 counting only the distinct ones).

The product of its digits is 24300, while the sum is 36.

The square root of 21355929 is about 4621.2475588308. The cubic root of 21355929 is about 277.4423936912.

The spelling of 21355929 in words is "twenty-one million, three hundred fifty-five thousand, nine hundred twenty-nine".