61720929 has 6 divisors (see below), whose sum is σ = 89152466. Its totient is φ = 41147280.

The previous prime is 61720913. The next prime is 61720933. The reversal of 61720929 is 92902716.

It can be written as a sum of positive squares in only one way, i.e., 42928704 + 18792225 = 6552^2 + 4335^2 .

It is not a de Polignac number, because 61720929 - 2⁴ = 61720913 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 61720893 and 61720902.

It is not an unprimeable number, because it can be changed into a prime (61720979) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3428932 + ... + 3428949.

Almost surely, 2^61720929 is an apocalyptic number.

It is an amenable number.

61720929 is a deficient number, since it is larger than the sum of its proper divisors (27431537).

61720929 is a wasteful number, since it uses less digits than its factorization.

61720929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6857887 (or 6857884 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 36.

The square root of 61720929 is about 7856.2668615571. The cubic root of 61720929 is about 395.1944329321.

The spelling of 61720929 in words is "sixty-one million, seven hundred twenty thousand, nine hundred twenty-nine".