61618521 has 4 divisors (see below), whose sum is σ = 82158032. Its totient is φ = 41079012.

The previous prime is 61618519. The next prime is 61618537. The reversal of 61618521 is 12581616.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 61618521 - 2¹ = 61618519 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61618511) 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, 10269751 + ... + 10269756.

It is an arithmetic number, because the mean of its divisors is an integer number (20539508).

Almost surely, 2^61618521 is an apocalyptic number.

It is an amenable number.

61618521 is a deficient number, since it is larger than the sum of its proper divisors (20539511).

61618521 is a wasteful number, since it uses less digits than its factorization.

61618521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20539510.

The product of its digits is 2880, while the sum is 30.

The square root of 61618521 is about 7849.7465564182. The cubic root of 61618521 is about 394.9757417138.

The spelling of 61618521 in words is "sixty-one million, six hundred eighteen thousand, five hundred twenty-one".