21087977089 has 9 divisors (see below), whose sum is σ = 22259198433. Its totient is φ = 19975469652.

The previous prime is 21087977069. The next prime is 21087977129. The reversal of 21087977089 is 98077978012.

The square root of 21087977089 is 145217.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 21087977089 - 2¹⁹ = 21087452801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21087977059) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2755302 + ... + 2762944.

Almost surely, 2^21087977089 is an apocalyptic number.

21087977089 is the 145217-th square number.

21087977089 is the 72609-th centered octagonal number.

It is an amenable number.

21087977089 is a deficient number, since it is larger than the sum of its proper divisors (1171221344).

21087977089 is an frugal number, since it uses more digits than its factorization.

21087977089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15324 (or 7662 counting only the distinct ones).

The product of its (nonzero) digits is 3556224, while the sum is 58.

The spelling of 21087977089 in words is "twenty-one billion, eighty-seven million, nine hundred seventy-seven thousand, eighty-nine".