2157664787 has 2 divisors, whose sum is σ = 2157664788. Its totient is φ = 2157664786.

The previous prime is 2157664783. The next prime is 2157664801. The reversal of 2157664787 is 7874667512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2157664787 - 2² = 2157664783 is a prime.

It is not a weakly prime, because it can be changed into another prime (2157664783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1078832393 + 1078832394.

It is an arithmetic number, because the mean of its divisors is an integer number (1078832394).

Almost surely, 2^2157664787 is an apocalyptic number.

2157664787 is a deficient number, since it is larger than the sum of its proper divisors (1).

2157664787 is an equidigital number, since it uses as much as digits as its factorization.

2157664787 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3951360, while the sum is 53.

The square root of 2157664787 is about 46450.6704687887. The cubic root of 2157664787 is about 1292.1948067930.

The spelling of 2157664787 in words is "two billion, one hundred fifty-seven million, six hundred sixty-four thousand, seven hundred eighty-seven".