21870778 has 8 divisors (see below), whose sum is σ = 32947668. Its totient is φ = 10888224.

The previous prime is 21870763. The next prime is 21870787. The reversal of 21870778 is 87707812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17614809 + 4255969 = 4197^2 + 2063^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 21870778.

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, 23001 + ... + 23932.

Almost surely, 2^21870778 is an apocalyptic number.

21870778 is a deficient number, since it is larger than the sum of its proper divisors (11076890).

21870778 is a wasteful number, since it uses less digits than its factorization.

21870778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47168.

The product of its (nonzero) digits is 43904, while the sum is 40.

The square root of 21870778 is about 4676.6203609017. The cubic root of 21870778 is about 279.6542415828.

The spelling of 21870778 in words is "twenty-one million, eight hundred seventy thousand, seven hundred seventy-eight".