61861639 has 4 divisors (see below), whose sum is σ = 70699024. Its totient is φ = 53024256.

The previous prime is 61861627. The next prime is 61861687. The reversal of 61861639 is 93616816.

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

It is a cyclic number.

It is not a de Polignac number, because 61861639 - 2⁵ = 61861607 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 (61861609) 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, 4418682 + ... + 4418695.

It is an arithmetic number, because the mean of its divisors is an integer number (17674756).

Almost surely, 2^61861639 is an apocalyptic number.

61861639 is a deficient number, since it is larger than the sum of its proper divisors (8837385).

61861639 is an equidigital number, since it uses as much as digits as its factorization.

61861639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8837384.

The product of its digits is 46656, while the sum is 40.

The square root of 61861639 is about 7865.2170345134. The cubic root of 61861639 is about 395.4945234913.

It can be divided in two parts, 61861 and 639, that added together give a square (62500 = 250²).

The spelling of 61861639 in words is "sixty-one million, eight hundred sixty-one thousand, six hundred thirty-nine".