61919681 has 2 divisors, whose sum is σ = 61919682. Its totient is φ = 61919680.

The previous prime is 61919677. The next prime is 61919707. The reversal of 61919681 is 18691916.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44622400 + 17297281 = 6680^2 + 4159^2 .

It is a cyclic number.

It is not a de Polignac number, because 61919681 - 2² = 61919677 is a prime.

It is a super-2 number, since 2×61919681² = 7668093790283522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (61919621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30959840 + 30959841.

It is an arithmetic number, because the mean of its divisors is an integer number (30959841).

Almost surely, 2^61919681 is an apocalyptic number.

It is an amenable number.

61919681 is a deficient number, since it is larger than the sum of its proper divisors (1).

61919681 is an equidigital number, since it uses as much as digits as its factorization.

61919681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 41.

The square root of 61919681 is about 7868.9059595347. The cubic root of 61919681 is about 395.6181764149.

The spelling of 61919681 in words is "sixty-one million, nine hundred nineteen thousand, six hundred eighty-one".