21294978 has 32 divisors (see below), whose sum is σ = 43872192. Its totient is φ = 6888000.

The previous prime is 21294937. The next prime is 21294989. The reversal of 21294978 is 87949212.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30028 + ... + 30728.

It is an arithmetic number, because the mean of its divisors is an integer number (1371006).

Almost surely, 2^21294978 is an apocalyptic number.

21294978 is an abundant number, since it is smaller than the sum of its proper divisors (22577214).

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

21294978 is a wasteful number, since it uses less digits than its factorization.

21294978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 850.

The product of its digits is 72576, while the sum is 42.

The square root of 21294978 is about 4614.6481989421. The cubic root of 21294978 is about 277.1781968863.

The spelling of 21294978 in words is "twenty-one million, two hundred ninety-four thousand, nine hundred seventy-eight".