21157607707 has 4 divisors (see below), whose sum is σ = 21157907400. Its totient is φ = 21157308016.

The previous prime is 21157607677. The next prime is 21157607717. The reversal of 21157607707 is 70770675112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21157607707 - 2¹¹ = 21157605659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21157607717) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20919 + ... + 206767.

It is an arithmetic number, because the mean of its divisors is an integer number (5289476850).

Almost surely, 2^21157607707 is an apocalyptic number.

21157607707 is a deficient number, since it is larger than the sum of its proper divisors (299693).

21157607707 is a wasteful number, since it uses less digits than its factorization.

21157607707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299692.

The product of its (nonzero) digits is 144060, while the sum is 43.

The spelling of 21157607707 in words is "twenty-one billion, one hundred fifty-seven million, six hundred seven thousand, seven hundred seven".