21030978 has 32 divisors (see below), whose sum is σ = 42900480. Its totient is φ = 6872400.

The previous prime is 21030973. The next prime is 21030979. The reversal of 21030978 is 87903012.

It is a happy number.

It is a super-3 number, since 3×21030978³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21030973) 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, 125851 + ... + 126017.

It is an arithmetic number, because the mean of its divisors is an integer number (1340640).

Almost surely, 2^21030978 is an apocalyptic number.

21030978 is an abundant number, since it is smaller than the sum of its proper divisors (21869502).

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

21030978 is a wasteful number, since it uses less digits than its factorization.

21030978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 462.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 21030978 is about 4585.9544262890. The cubic root of 21030978 is about 276.0280112297.

The spelling of 21030978 in words is "twenty-one million, thirty thousand, nine hundred seventy-eight".