1621605157 has 4 divisors (see below), whose sum is σ = 1632344416. Its totient is φ = 1610865900.

The previous prime is 1621605131. The next prime is 1621605173. The reversal of 1621605157 is 7515061261.

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 1621605157 - 2¹⁵ = 1621572389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621605127) 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, 5369403 + ... + 5369704.

It is an arithmetic number, because the mean of its divisors is an integer number (408086104).

Almost surely, 2^1621605157 is an apocalyptic number.

It is an amenable number.

1621605157 is a deficient number, since it is larger than the sum of its proper divisors (10739259).

1621605157 is a wasteful number, since it uses less digits than its factorization.

1621605157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10739258.

The product of its (nonzero) digits is 12600, while the sum is 34.

The square root of 1621605157 is about 40269.1588812083. The cubic root of 1621605157 is about 1174.8480641329.

The spelling of 1621605157 in words is "one billion, six hundred twenty-one million, six hundred five thousand, one hundred fifty-seven".