21554113551 has 8 divisors (see below), whose sum is σ = 30251387520. Its totient is φ = 13613124312.

The previous prime is 21554113541. The next prime is 21554113577. The reversal of 21554113551 is 15531145512.

It is a happy number.

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

It is not a de Polignac number, because 21554113551 - 2⁵ = 21554113519 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554113501) 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, 189071115 + ... + 189071228.

It is an arithmetic number, because the mean of its divisors is an integer number (3781423440).

Almost surely, 2^21554113551 is an apocalyptic number.

21554113551 is a deficient number, since it is larger than the sum of its proper divisors (8697273969).

21554113551 is a wasteful number, since it uses less digits than its factorization.

21554113551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 378142365.

The product of its digits is 15000, while the sum is 33.

The spelling of 21554113551 in words is "twenty-one billion, five hundred fifty-four million, one hundred thirteen thousand, five hundred fifty-one".