21072781587 has 64 divisors (see below), whose sum is σ = 33468019200. Its totient is φ = 11625984000.

The previous prime is 21072781577. The next prime is 21072781591. The reversal of 21072781587 is 78518727012.

It is a happy number.

It is not a de Polignac number, because 21072781587 - 2⁴ = 21072781571 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21072781537) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 14522212 + ... + 14523662.

It is an arithmetic number, because the mean of its divisors is an integer number (522937800).

Almost surely, 2^21072781587 is an apocalyptic number.

21072781587 is a deficient number, since it is larger than the sum of its proper divisors (12395237613).

21072781587 is a wasteful number, since it uses less digits than its factorization.

21072781587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1924.

The product of its (nonzero) digits is 439040, while the sum is 48.

The spelling of 21072781587 in words is "twenty-one billion, seventy-two million, seven hundred eighty-one thousand, five hundred eighty-seven".