20624991 has 4 divisors (see below), whose sum is σ = 27499992. Its totient is φ = 13749992.

The previous prime is 20624987. The next prime is 20625019. The reversal of 20624991 is 19942602.

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 20624991 - 2² = 20624987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20624911) 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, 3437496 + ... + 3437501.

It is an arithmetic number, because the mean of its divisors is an integer number (6874998).

Almost surely, 2^20624991 is an apocalyptic number.

20624991 is a deficient number, since it is larger than the sum of its proper divisors (6875001).

20624991 is an equidigital number, since it uses as much as digits as its factorization.

20624991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6875000.

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 20624991 is about 4541.4745402787. The cubic root of 20624991 is about 274.2402877321.

The spelling of 20624991 in words is "twenty million, six hundred twenty-four thousand, nine hundred ninety-one".