61961215521 has 8 divisors (see below), whose sum is σ = 82616112000. Its totient is φ = 41306898032.

The previous prime is 61961215513. The next prime is 61961215541. The reversal of 61961215521 is 12551216916.

61961215521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 61961215521 - 2³ = 61961215513 is a prime.

It is a super-2 number, since 2×61961215521² (a number of 22 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 61961215521.

It is not an unprimeable number, because it can be changed into a prime (61961215501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 301480 + ... + 463478.

It is an arithmetic number, because the mean of its divisors is an integer number (10327014000).

Almost surely, 2^61961215521 is an apocalyptic number.

It is an amenable number.

61961215521 is a deficient number, since it is larger than the sum of its proper divisors (20654896479).

61961215521 is a wasteful number, since it uses less digits than its factorization.

61961215521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 289495.

The product of its digits is 32400, while the sum is 39.

The spelling of 61961215521 in words is "sixty-one billion, nine hundred sixty-one million, two hundred fifteen thousand, five hundred twenty-one".