621664718 has 4 divisors (see below), whose sum is σ = 932497080. Its totient is φ = 310832358.

The previous prime is 621664691. The next prime is 621664739. The reversal of 621664718 is 817466126.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 817466126 = 2 ⋅408733063.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 155416178 + ... + 155416181.

It is an arithmetic number, because the mean of its divisors is an integer number (233124270).

Almost surely, 2^621664718 is an apocalyptic number.

621664718 is a deficient number, since it is larger than the sum of its proper divisors (310832362).

621664718 is a wasteful number, since it uses less digits than its factorization.

621664718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310832361.

The product of its digits is 96768, while the sum is 41.

The square root of 621664718 is about 24933.2051289039. The cubic root of 621664718 is about 853.4643927459.

The spelling of 621664718 in words is "six hundred twenty-one million, six hundred sixty-four thousand, seven hundred eighteen".