21557157715642 has 8 divisors (see below), whose sum is σ = 32335756588800. Its totient is φ = 10778572186044.

The previous prime is 21557157715633. The next prime is 21557157715673. The reversal of 21557157715642 is 24651775175512.

It is a happy number.

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

It is a super-2 number, since 2×21557157715642² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3525709 + ... + 7452847.

It is an arithmetic number, because the mean of its divisors is an integer number (4041969573600).

Almost surely, 2^{21557157715642} is an apocalyptic number.

21557157715642 is a deficient number, since it is larger than the sum of its proper divisors (10778598873158).

21557157715642 is a wasteful number, since it uses less digits than its factorization.

21557157715642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6671780.

The product of its digits is 20580000, while the sum is 58.

The spelling of 21557157715642 in words is "twenty-one trillion, five hundred fifty-seven billion, one hundred fifty-seven million, seven hundred fifteen thousand, six hundred forty-two".