21620767 has 16 divisors (see below), whose sum is σ = 25468992. Its totient is φ = 17971200.

The previous prime is 21620749. The next prime is 21620789. The reversal of 21620767 is 76702612.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21620767 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 (21620737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37183 + ... + 37759.

It is an arithmetic number, because the mean of its divisors is an integer number (1591812).

Almost surely, 2^21620767 is an apocalyptic number.

21620767 is a deficient number, since it is larger than the sum of its proper divisors (3848225).

21620767 is a wasteful number, since it uses less digits than its factorization.

21620767 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 738.

The product of its (nonzero) digits is 7056, while the sum is 31.

The square root of 21620767 is about 4649.8136521801. The cubic root of 21620767 is about 278.5845531652.

The spelling of 21620767 in words is "twenty-one million, six hundred twenty thousand, seven hundred sixty-seven".