20621705 has 8 divisors (see below), whose sum is σ = 26649672. Its totient is φ = 15228288.

The previous prime is 20621693. The next prime is 20621759. The reversal of 20621705 is 50712602.

It can be written as a sum of positive squares in 4 ways, for example, as 1024 + 20620681 = 32^2 + 4541^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20621705 - 2²² = 16427401 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 158564 + ... + 158693.

It is an arithmetic number, because the mean of its divisors is an integer number (3331209).

Almost surely, 2^20621705 is an apocalyptic number.

It is an amenable number.

20621705 is a deficient number, since it is larger than the sum of its proper divisors (6027967).

20621705 is a wasteful number, since it uses less digits than its factorization.

20621705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 317275.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 20621705 is about 4541.1127490958. The cubic root of 20621705 is about 274.2257228539.

The spelling of 20621705 in words is "twenty million, six hundred twenty-one thousand, seven hundred five".