61991915 has 16 divisors (see below), whose sum is σ = 75479040. Its totient is φ = 48874080.

The previous prime is 61991899. The next prime is 61991987. The reversal of 61991915 is 51919916.

It is not a de Polignac number, because 61991915 - 2⁴ = 61991899 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 132512 + ... + 132978.

It is an arithmetic number, because the mean of its divisors is an integer number (4717440).

Almost surely, 2^61991915 is an apocalyptic number.

61991915 is a deficient number, since it is larger than the sum of its proper divisors (13487125).

61991915 is a wasteful number, since it uses less digits than its factorization.

61991915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 802.

The product of its digits is 21870, while the sum is 41.

The square root of 61991915 is about 7873.4944592601. The cubic root of 61991915 is about 395.7719561591.

The spelling of 61991915 in words is "sixty-one million, nine hundred ninety-one thousand, nine hundred fifteen".