621791906 has 8 divisors (see below), whose sum is σ = 938629020. Its totient is φ = 308915568.

The previous prime is 621791903. The next prime is 621791909. The reversal of 621791906 is 609197126.

It is an interprime number because it is at equal distance from previous prime (621791903) and next prime (621791909).

It can be written as a sum of positive squares in 2 ways, for example, as 617969881 + 3822025 = 24859^2 + 1955^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×621791906² = 773250348734225672, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (621791903) 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, 989801 + ... + 990428.

Almost surely, 2^621791906 is an apocalyptic number.

621791906 is a deficient number, since it is larger than the sum of its proper divisors (316837114).

621791906 is a wasteful number, since it uses less digits than its factorization.

621791906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1980388.

The product of its (nonzero) digits is 40824, while the sum is 41.

The square root of 621791906 is about 24935.7555730722. The cubic root of 621791906 is about 853.5225929429.

The spelling of 621791906 in words is "six hundred twenty-one million, seven hundred ninety-one thousand, nine hundred six".