61621591 has 4 divisors (see below), whose sum is σ = 61660872. Its totient is φ = 61582312.

The previous prime is 61621589. The next prime is 61621597. The reversal of 61621591 is 19512616.

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

It is a cyclic number.

It is not a de Polignac number, because 61621591 - 2¹ = 61621589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61621597) 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, 17185 + ... + 20458.

It is an arithmetic number, because the mean of its divisors is an integer number (15415218).

Almost surely, 2^61621591 is an apocalyptic number.

61621591 is a deficient number, since it is larger than the sum of its proper divisors (39281).

61621591 is a wasteful number, since it uses less digits than its factorization.

61621591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39280.

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

The square root of 61621591 is about 7849.9421016973. The cubic root of 61621591 is about 394.9823011885.

The spelling of 61621591 in words is "sixty-one million, six hundred twenty-one thousand, five hundred ninety-one".