61721455 has 4 divisors (see below), whose sum is σ = 74065752. Its totient is φ = 49377160.

The previous prime is 61721453. The next prime is 61721497. The reversal of 61721455 is 55412716.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 61721455 - 2¹ = 61721453 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61721453) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6172141 + ... + 6172150.

It is an arithmetic number, because the mean of its divisors is an integer number (18516438).

Almost surely, 2^61721455 is an apocalyptic number.

61721455 is a deficient number, since it is larger than the sum of its proper divisors (12344297).

61721455 is a wasteful number, since it uses less digits than its factorization.

61721455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12344296.

The product of its digits is 8400, while the sum is 31.

The square root of 61721455 is about 7856.3003379453. The cubic root of 61721455 is about 395.1955555750.

The spelling of 61721455 in words is "sixty-one million, seven hundred twenty-one thousand, four hundred fifty-five".