61638779 has 2 divisors, whose sum is σ = 61638780. Its totient is φ = 61638778.

The previous prime is 61638769. The next prime is 61638809. The reversal of 61638779 is 97783616.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61638779 is a prime.

It is a super-2 number, since 2×61638779² = 7598678153221682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (61638749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30819389 + 30819390.

It is an arithmetic number, because the mean of its divisors is an integer number (30819390).

Almost surely, 2^61638779 is an apocalyptic number.

61638779 is a deficient number, since it is larger than the sum of its proper divisors (1).

61638779 is an equidigital number, since it uses as much as digits as its factorization.

61638779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 381024, while the sum is 47.

The square root of 61638779 is about 7851.0368105111. The cubic root of 61638779 is about 395.0190216765.

The spelling of 61638779 in words is "sixty-one million, six hundred thirty-eight thousand, seven hundred seventy-nine".