2157664987 has 4 divisors (see below), whose sum is σ = 2194235640. Its totient is φ = 2121094336.

The previous prime is 2157664979. The next prime is 2157664991. The reversal of 2157664987 is 7894667512.

2157664987 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 2157664987 - 2³ = 2157664979 is a prime.

It is a super-2 number, since 2×2157664987² = 9311036392251420338, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2157664907) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18285238 + ... + 18285355.

It is an arithmetic number, because the mean of its divisors is an integer number (548558910).

Almost surely, 2^2157664987 is an apocalyptic number.

2157664987 is a deficient number, since it is larger than the sum of its proper divisors (36570653).

2157664987 is an equidigital number, since it uses as much as digits as its factorization.

2157664987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36570652.

The product of its digits is 5080320, while the sum is 55.

The square root of 2157664987 is about 46450.6726216101. The cubic root of 2157664987 is about 1292.1948467187.

The spelling of 2157664987 in words is "two billion, one hundred fifty-seven million, six hundred sixty-four thousand, nine hundred eighty-seven".