21157771037 has 4 divisors (see below), whose sum is σ = 22785291900. Its totient is φ = 19530250176.

The previous prime is 21157770983. The next prime is 21157771069. The reversal of 21157771037 is 73017775112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10621569721 + 10536201316 = 103061^2 + 102646^2 .

It is a cyclic number.

It is not a de Polignac number, because 21157771037 - 2¹⁶ = 21157705501 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21157770985 and 21157771003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21157771097) 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, 813760412 + ... + 813760437.

It is an arithmetic number, because the mean of its divisors is an integer number (5696322975).

Almost surely, 2^21157771037 is an apocalyptic number.

It is an amenable number.

21157771037 is a deficient number, since it is larger than the sum of its proper divisors (1627520863).

21157771037 is a wasteful number, since it uses less digits than its factorization.

21157771037 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1627520862.

The product of its (nonzero) digits is 72030, while the sum is 41.

The spelling of 21157771037 in words is "twenty-one billion, one hundred fifty-seven million, seven hundred seventy-one thousand, thirty-seven".