61978537 has 4 divisors (see below), whose sum is σ = 64673280. Its totient is φ = 59283796.

The previous prime is 61978531. The next prime is 61978547. The reversal of 61978537 is 73587916.

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 a cyclic number.

It is not a de Polignac number, because 61978537 - 2⁷ = 61978409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61978531) 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, 1347337 + ... + 1347382.

It is an arithmetic number, because the mean of its divisors is an integer number (16168320).

Almost surely, 2^61978537 is an apocalyptic number.

It is an amenable number.

61978537 is a deficient number, since it is larger than the sum of its proper divisors (2694743).

61978537 is a wasteful number, since it uses less digits than its factorization.

61978537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2694742.

The product of its digits is 317520, while the sum is 46.

The square root of 61978537 is about 7872.6448541770. The cubic root of 61978537 is about 395.7434846068.

The spelling of 61978537 in words is "sixty-one million, nine hundred seventy-eight thousand, five hundred thirty-seven".