21371577878 has 32 divisors (see below), whose sum is σ = 37849835520. Its totient is φ = 8856521280.

The previous prime is 21371577827. The next prime is 21371577923. The reversal of 21371577878 is 87877517312.

It is a Curzon number.

It is a congruent number.

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, 526850 + ... + 565962.

It is an arithmetic number, because the mean of its divisors is an integer number (1182807360).

Almost surely, 2^21371577878 is an apocalyptic number.

21371577878 is a deficient number, since it is larger than the sum of its proper divisors (16478257642).

21371577878 is a wasteful number, since it uses less digits than its factorization.

21371577878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40412.

The product of its digits is 4609920, while the sum is 56.

The spelling of 21371577878 in words is "twenty-one billion, three hundred seventy-one million, five hundred seventy-seven thousand, eight hundred seventy-eight".