61491421 has 2 divisors, whose sum is σ = 61491422. Its totient is φ = 61491420.

The previous prime is 61491413. The next prime is 61491427. The reversal of 61491421 is 12419416.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 46172025 + 15319396 = 6795^2 + 3914^2 .

It is a cyclic number.

It is not a de Polignac number, because 61491421 - 2³ = 61491413 is a prime.

It is equal to p_3645307 and since 61491421 and 3645307 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 61491421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61491427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30745710 + 30745711.

It is an arithmetic number, because the mean of its divisors is an integer number (30745711).

Almost surely, 2^61491421 is an apocalyptic number.

It is an amenable number.

61491421 is a deficient number, since it is larger than the sum of its proper divisors (1).

61491421 is an equidigital number, since it uses as much as digits as its factorization.

61491421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 28.

The square root of 61491421 is about 7841.6465745403. The cubic root of 61491421 is about 394.7039837410.

The spelling of 61491421 in words is "sixty-one million, four hundred ninety-one thousand, four hundred twenty-one".