20147621 has 4 divisors (see below), whose sum is σ = 21697452. Its totient is φ = 18597792.

The previous prime is 20147597. The next prime is 20147623. The reversal of 20147621 is 12674102.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6002500 + 14145121 = 2450^2 + 3761^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20147621 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20147623) 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, 774896 + ... + 774921.

It is an arithmetic number, because the mean of its divisors is an integer number (5424363).

Almost surely, 2^20147621 is an apocalyptic number.

It is an amenable number.

20147621 is a deficient number, since it is larger than the sum of its proper divisors (1549831).

20147621 is a wasteful number, since it uses less digits than its factorization.

20147621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1549830.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 20147621 is about 4488.6101412353. The cubic root of 20147621 is about 272.1079669782.

The spelling of 20147621 in words is "twenty million, one hundred forty-seven thousand, six hundred twenty-one".