21204078 has 32 divisors (see below), whose sum is σ = 48625920. Its totient is φ = 6038400.

The previous prime is 21204077. The next prime is 21204107. The reversal of 21204078 is 87040212.

It is a super-2 number, since 2×21204078² = 899225847660168, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204077) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16213 + ... + 17471.

It is an arithmetic number, because the mean of its divisors is an integer number (1519560).

Almost surely, 2^21204078 is an apocalyptic number.

21204078 is an abundant number, since it is smaller than the sum of its proper divisors (27421842).

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

21204078 is a wasteful number, since it uses less digits than its factorization.

21204078 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1672.

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 21204078 is about 4604.7885944960. The cubic root of 21204078 is about 276.7832456558.

The spelling of 21204078 in words is "twenty-one million, two hundred four thousand, seventy-eight".