2157961961 has 4 divisors (see below), whose sum is σ = 2178913152. Its totient is φ = 2137010772.

The previous prime is 2157961951. The next prime is 2157961969. The reversal of 2157961961 is 1691697512.

2157961961 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2157961961 - 2²² = 2153767657 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2157961969) 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, 10475441 + ... + 10475646.

It is an arithmetic number, because the mean of its divisors is an integer number (544728288).

Almost surely, 2^2157961961 is an apocalyptic number.

It is an amenable number.

2157961961 is a deficient number, since it is larger than the sum of its proper divisors (20951191).

2157961961 is a wasteful number, since it uses less digits than its factorization.

2157961961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20951190.

The product of its digits is 204120, while the sum is 47.

The square root of 2157961961 is about 46453.8691714695. The cubic root of 2157961961 is about 1292.2541284994.

It can be divided in two parts, 2157961 and 961, that multiplied together give a square (2073800521 = 45539²).

The spelling of 2157961961 in words is "two billion, one hundred fifty-seven million, nine hundred sixty-one thousand, nine hundred sixty-one".