21787085621 has 8 divisors (see below), whose sum is σ = 24922357824. Its totient is φ = 18657521280.

The previous prime is 21787085591. The next prime is 21787085633. The reversal of 21787085621 is 12658078712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21787085621 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21787085321) 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, 1418780 + ... + 1434053.

It is an arithmetic number, because the mean of its divisors is an integer number (3115294728).

Almost surely, 2^21787085621 is an apocalyptic number.

It is an amenable number.

21787085621 is a deficient number, since it is larger than the sum of its proper divisors (3135272203).

21787085621 is a wasteful number, since it uses less digits than its factorization.

21787085621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2853931.

The product of its (nonzero) digits is 376320, while the sum is 47.

The spelling of 21787085621 in words is "twenty-one billion, seven hundred eighty-seven million, eighty-five thousand, six hundred twenty-one".