621642557 has 2 divisors, whose sum is σ = 621642558. Its totient is φ = 621642556.

The previous prime is 621642431. The next prime is 621642607. The reversal of 621642557 is 755246126.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 545969956 + 75672601 = 23366^2 + 8699^2 .

It is a cyclic number.

It is not a de Polignac number, because 621642557 - 2²⁴ = 604865341 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 621642557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (621642157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310821278 + 310821279.

It is an arithmetic number, because the mean of its divisors is an integer number (310821279).

Almost surely, 2^621642557 is an apocalyptic number.

It is an amenable number.

621642557 is a deficient number, since it is larger than the sum of its proper divisors (1).

621642557 is an equidigital number, since it uses as much as digits as its factorization.

621642557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 100800, while the sum is 38.

The square root of 621642557 is about 24932.7607175780. The cubic root of 621642557 is about 853.4542512400.

The spelling of 621642557 in words is "six hundred twenty-one million, six hundred forty-two thousand, five hundred fifty-seven".