61581220651 has 4 divisors (see below), whose sum is σ = 61596662400. Its totient is φ = 61565778904.

The previous prime is 61581220633. The next prime is 61581220669. The reversal of 61581220651 is 15602218516.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (61581220633) and next prime (61581220669).

It is a cyclic number.

It is not a de Polignac number, because 61581220651 - 2¹⁵ = 61581187883 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 61581220651.

It is not an unprimeable number, because it can be changed into a prime (61581220601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7714891 + ... + 7722868.

It is an arithmetic number, because the mean of its divisors is an integer number (15399165600).

Almost surely, 2^61581220651 is an apocalyptic number.

61581220651 is a deficient number, since it is larger than the sum of its proper divisors (15441749).

61581220651 is a wasteful number, since it uses less digits than its factorization.

61581220651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15441748.

The product of its (nonzero) digits is 28800, while the sum is 37.

The spelling of 61581220651 in words is "sixty-one billion, five hundred eighty-one million, two hundred twenty thousand, six hundred fifty-one".