21105657478 has 8 divisors (see below), whose sum is σ = 31889570472. Its totient is φ = 10475800656.

The previous prime is 21105657457. The next prime is 21105657487. The reversal of 21105657478 is 87475650112.

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

It is a congruent number.

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, 38513700 + ... + 38514247.

It is an arithmetic number, because the mean of its divisors is an integer number (3986196309).

Almost surely, 2^21105657478 is an apocalyptic number.

21105657478 is a deficient number, since it is larger than the sum of its proper divisors (10783912994).

21105657478 is a wasteful number, since it uses less digits than its factorization.

21105657478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77028086.

The product of its (nonzero) digits is 470400, while the sum is 46.

The spelling of 21105657478 in words is "twenty-one billion, one hundred five million, six hundred fifty-seven thousand, four hundred seventy-eight".