21457901 has 4 divisors (see below), whose sum is σ = 21729600. Its totient is φ = 21186204.

The previous prime is 21457871. The next prime is 21457939. The reversal of 21457901 is 10975412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21457901 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 (21457981) 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, 135731 + ... + 135888.

It is an arithmetic number, because the mean of its divisors is an integer number (5432400).

Almost surely, 2^21457901 is an apocalyptic number.

It is an amenable number.

21457901 is a deficient number, since it is larger than the sum of its proper divisors (271699).

21457901 is an equidigital number, since it uses as much as digits as its factorization.

21457901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271698.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 21457901 is about 4632.2673713852. The cubic root of 21457901 is about 277.8832774315.

The spelling of 21457901 in words is "twenty-one million, four hundred fifty-seven thousand, nine hundred one".