21655515562 has 4 divisors (see below), whose sum is σ = 32483273346. Its totient is φ = 10827757780.

The previous prime is 21655515559. The next prime is 21655515577. The reversal of 21655515562 is 26551555612.

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

It can be written as a sum of positive squares in only one way, i.e., 17056098801 + 4599416761 = 130599^2 + 67819^2 .

It is a super-2 number, since 2×21655515562² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5413878889 + ... + 5413878892.

Almost surely, 2^21655515562 is an apocalyptic number.

21655515562 is a deficient number, since it is larger than the sum of its proper divisors (10827757784).

21655515562 is a wasteful number, since it uses less digits than its factorization.

21655515562 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10827757783.

The product of its digits is 450000, while the sum is 43.

The spelling of 21655515562 in words is "twenty-one billion, six hundred fifty-five million, five hundred fifteen thousand, five hundred sixty-two".