20992978 has 8 divisors (see below), whose sum is σ = 31512780. Its totient is φ = 10488720.

The previous prime is 20992969. The next prime is 20992981. The reversal of 20992978 is 87929902.

It can be written as a sum of positive squares in 2 ways, for example, as 20729809 + 263169 = 4553^2 + 513^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 468 + ... + 6496.

Almost surely, 2^20992978 is an apocalyptic number.

20992978 is a deficient number, since it is larger than the sum of its proper divisors (10519802).

20992978 is a wasteful number, since it uses less digits than its factorization.

20992978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7772.

The product of its (nonzero) digits is 163296, while the sum is 46.

The square root of 20992978 is about 4581.8094678849. The cubic root of 20992978 is about 275.8616631535.

The spelling of 20992978 in words is "twenty million, nine hundred ninety-two thousand, nine hundred seventy-eight".