21288732761 has 8 divisors (see below), whose sum is σ = 22789010400. Its totient is φ = 19826436960.

The previous prime is 21288732739. The next prime is 21288732779. The reversal of 21288732761 is 16723788212.

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

It is a cyclic number.

It is not a de Polignac number, because 21288732761 - 2⁶ = 21288732697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21288732721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9494300 + ... + 9496541.

It is an arithmetic number, because the mean of its divisors is an integer number (2848626300).

Almost surely, 2^21288732761 is an apocalyptic number.

It is an amenable number.

21288732761 is a deficient number, since it is larger than the sum of its proper divisors (1500277639).

21288732761 is a wasteful number, since it uses less digits than its factorization.

21288732761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18990919.

The product of its digits is 451584, while the sum is 47.

The spelling of 21288732761 in words is "twenty-one billion, two hundred eighty-eight million, seven hundred thirty-two thousand, seven hundred sixty-one".