157121621 has 4 divisors (see below), whose sum is σ = 165391200. Its totient is φ = 148852044.

The previous prime is 157121603. The next prime is 157121639. The reversal of 157121621 is 126121751.

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 an interprime number because it is at equal distance from previous prime (157121603) and next prime (157121639).

It is a cyclic number.

It is not a de Polignac number, because 157121621 - 2⁶ = 157121557 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (157121221) 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, 4134761 + ... + 4134798.

It is an arithmetic number, because the mean of its divisors is an integer number (41347800).

Almost surely, 2^157121621 is an apocalyptic number.

It is an amenable number.

157121621 is a deficient number, since it is larger than the sum of its proper divisors (8269579).

157121621 is an equidigital number, since it uses as much as digits as its factorization.

157121621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8269578.

The product of its digits is 840, while the sum is 26.

The square root of 157121621 is about 12534.8163528629. The cubic root of 157121621 is about 539.6083362498.

The spelling of 157121621 in words is "one hundred fifty-seven million, one hundred twenty-one thousand, six hundred twenty-one".