61978587021 has 80 divisors (see below), whose sum is σ = 100556273664. Its totient is φ = 37817559936.

The previous prime is 61978587019. The next prime is 61978587067. The reversal of 61978587021 is 12078587916.

It is not a de Polignac number, because 61978587021 - 2¹ = 61978587019 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61978587221) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 91548535 + ... + 91549211.

Almost surely, 2^61978587021 is an apocalyptic number.

It is an amenable number.

61978587021 is a deficient number, since it is larger than the sum of its proper divisors (38577686643).

61978587021 is a wasteful number, since it uses less digits than its factorization.

61978587021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1312 (or 1303 counting only the distinct ones).

The product of its (nonzero) digits is 1693440, while the sum is 54.

The spelling of 61978587021 in words is "sixty-one billion, nine hundred seventy-eight million, five hundred eighty-seven thousand, twenty-one".