21029856 has 48 divisors (see below), whose sum is σ = 55440000. Its totient is φ = 6979968.

The previous prime is 21029839. The next prime is 21029857. The reversal of 21029856 is 65892012.

21029856 = T₂₂₉ + T₂₃₀ + ... + T₅₁₆.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21029857) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41895 + ... + 42393.

It is an arithmetic number, because the mean of its divisors is an integer number (1155000).

Almost surely, 2^21029856 is an apocalyptic number.

It is an amenable number.

21029856 is an abundant number, since it is smaller than the sum of its proper divisors (34410144).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21029856 is a wasteful number, since it uses less digits than its factorization.

21029856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 951 (or 943 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21029856 is about 4585.8320946149. The cubic root of 21029856 is about 276.0231024560.

The spelling of 21029856 in words is "twenty-one million, twenty-nine thousand, eight hundred fifty-six".