157661639 has 4 divisors (see below), whose sum is σ = 165959640. Its totient is φ = 149363640.

The previous prime is 157661627. The next prime is 157661657. The reversal of 157661639 is 936166751.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 936166751 = 13 ⋅72012827.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-157661639 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 157661639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (157661659) 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, 4148972 + ... + 4149009.

It is an arithmetic number, because the mean of its divisors is an integer number (41489910).

Almost surely, 2^157661639 is an apocalyptic number.

157661639 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

157661639 is a deficient number, since it is larger than the sum of its proper divisors (8298001).

157661639 is an equidigital number, since it uses as much as digits as its factorization.

157661639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8298000.

The product of its digits is 204120, while the sum is 44.

The square root of 157661639 is about 12556.3385984928. The cubic root of 157661639 is about 540.2258303264.

The spelling of 157661639 in words is "one hundred fifty-seven million, six hundred sixty-one thousand, six hundred thirty-nine".