21554402636 has 72 divisors (see below), whose sum is σ = 43084641600. Its totient is φ = 9404890560.

The previous prime is 21554402621. The next prime is 21554402657. The reversal of 21554402636 is 63620445512.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is a self number, because there is not a number n which added to its sum of digits gives 21554402636.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7332455 + ... + 7335393.

It is an arithmetic number, because the mean of its divisors is an integer number (598397800).

Almost surely, 2^21554402636 is an apocalyptic number.

21554402636 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21554402636 is a deficient number, since it is larger than the sum of its proper divisors (21530238964).

21554402636 is a wasteful number, since it uses less digits than its factorization.

21554402636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3559 (or 3544 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 38.

The spelling of 21554402636 in words is "twenty-one billion, five hundred fifty-four million, four hundred two thousand, six hundred thirty-six".