61691251 has 2 divisors, whose sum is σ = 61691252. Its totient is φ = 61691250.

The previous prime is 61691243. The next prime is 61691263. The reversal of 61691251 is 15219616.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 61691251 - 2³ = 61691243 is a prime.

It is not a weakly prime, because it can be changed into another prime (61491251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30845625 + 30845626.

It is an arithmetic number, because the mean of its divisors is an integer number (30845626).

Almost surely, 2^61691251 is an apocalyptic number.

61691251 is a deficient number, since it is larger than the sum of its proper divisors (1).

61691251 is an equidigital number, since it uses as much as digits as its factorization.

61691251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 31.

The square root of 61691251 is about 7854.3778238636. The cubic root of 61691251 is about 395.1310807817.

The spelling of 61691251 in words is "sixty-one million, six hundred ninety-one thousand, two hundred fifty-one".