61387821021 has 16 divisors (see below), whose sum is σ = 84510433280. Its totient is φ = 39595826160.

The previous prime is 61387820999. The next prime is 61387821023. The reversal of 61387821021 is 12012878316.

It is not a de Polignac number, because 61387821021 - 2⁶ = 61387820957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61387821023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 336720 + ... + 485958.

It is an arithmetic number, because the mean of its divisors is an integer number (5281902080).

Almost surely, 2^61387821021 is an apocalyptic number.

It is an amenable number.

61387821021 is a deficient number, since it is larger than the sum of its proper divisors (23122612259).

61387821021 is a wasteful number, since it uses less digits than its factorization.

61387821021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153696.

The product of its (nonzero) digits is 32256, while the sum is 39.

The spelling of 61387821021 in words is "sixty-one billion, three hundred eighty-seven million, eight hundred twenty-one thousand, twenty-one".