61978881 has 4 divisors (see below), whose sum is σ = 82638512. Its totient is φ = 41319252.

The previous prime is 61978871. The next prime is 61978883. The reversal of 61978881 is 18887916.

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 61978881 - 2¹⁰ = 61977857 is a prime.

It is a super-2 number, since 2×61978881² = 7682763380024322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 61978881.

It is not an unprimeable number, because it can be changed into a prime (61978883) 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, 10329811 + ... + 10329816.

It is an arithmetic number, because the mean of its divisors is an integer number (20659628).

Almost surely, 2^61978881 is an apocalyptic number.

It is an amenable number.

61978881 is a deficient number, since it is larger than the sum of its proper divisors (20659631).

61978881 is a wasteful number, since it uses less digits than its factorization.

61978881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20659630.

The product of its digits is 193536, while the sum is 48.

The square root of 61978881 is about 7872.6667019505. Note that the first 3 decimals coincide. The cubic root of 61978881 is about 395.7442167716.

The spelling of 61978881 in words is "sixty-one million, nine hundred seventy-eight thousand, eight hundred eighty-one".