620661031991 has 32 divisors (see below), whose sum is σ = 853660394496. Its totient is φ = 435540960000.

The previous prime is 620661031987. The next prime is 620661031999. The reversal of 620661031991 is 199130166026.

It is a cyclic number.

It is not a de Polignac number, because 620661031991 - 2² = 620661031987 is a prime.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (620661031999) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7520435 + ... + 7602516.

It is an arithmetic number, because the mean of its divisors is an integer number (26676887328).

Almost surely, 2^620661031991 is an apocalyptic number.

620661031991 is a deficient number, since it is larger than the sum of its proper divisors (232999362505).

620661031991 is a wasteful number, since it uses less digits than its factorization.

620661031991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15123023.

The product of its (nonzero) digits is 104976, while the sum is 44.

The spelling of 620661031991 in words is "six hundred twenty billion, six hundred sixty-one million, thirty-one thousand, nine hundred ninety-one".