21550142691 has 32 divisors (see below), whose sum is σ = 39804019200. Its totient is φ = 11194878240.

The previous prime is 21550142681. The next prime is 21550142711. The reversal of 21550142691 is 19624105512.

21550142691 is a `hidden beast` number, since 2 + 1 + 550 + 1 + 42 + 69 + 1 = 666.

It is not a de Polignac number, because 21550142691 - 2²² = 21545948387 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21550142641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5180736 + ... + 5184893.

It is an arithmetic number, because the mean of its divisors is an integer number (1243875600).

Almost surely, 2^21550142691 is an apocalyptic number.

21550142691 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21550142691 is a deficient number, since it is larger than the sum of its proper divisors (18253876509).

21550142691 is a wasteful number, since it uses less digits than its factorization.

21550142691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10365656 (or 10365650 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The spelling of 21550142691 in words is "twenty-one billion, five hundred fifty million, one hundred forty-two thousand, six hundred ninety-one".