61662721 has 2 divisors, whose sum is σ = 61662722. Its totient is φ = 61662720.

The previous prime is 61662703. The next prime is 61662749. The reversal of 61662721 is 12726616.

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., 32890225 + 28772496 = 5735^2 + 5364^2 .

It is a cyclic number.

It is not a de Polignac number, because 61662721 - 2¹⁹ = 61138433 is a prime.

It is a super-2 number, since 2×61662721² = 7604582322247682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (61662761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30831360 + 30831361.

It is an arithmetic number, because the mean of its divisors is an integer number (30831361).

Almost surely, 2^61662721 is an apocalyptic number.

It is an amenable number.

61662721 is a deficient number, since it is larger than the sum of its proper divisors (1).

61662721 is an equidigital number, since it uses as much as digits as its factorization.

61662721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 31.

The square root of 61662721 is about 7852.5614292408. The cubic root of 61662721 is about 395.0701600525.

The spelling of 61662721 in words is "sixty-one million, six hundred sixty-two thousand, seven hundred twenty-one".