21940157 has 4 divisors (see below), whose sum is σ = 22647936. Its totient is φ = 21232380.

The previous prime is 21940151. The next prime is 21940159. The reversal of 21940157 is 75104912.

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 not a de Polignac number, because 21940157 - 2¹⁰ = 21939133 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 (21940151) 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, 353843 + ... + 353904.

It is an arithmetic number, because the mean of its divisors is an integer number (5661984).

Almost surely, 2^21940157 is an apocalyptic number.

It is an amenable number.

21940157 is a deficient number, since it is larger than the sum of its proper divisors (707779).

21940157 is an equidigital number, since it uses as much as digits as its factorization.

21940157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 707778.

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

The square root of 21940157 is about 4684.0321305474. The cubic root of 21940157 is about 279.9496380511.

The spelling of 21940157 in words is "twenty-one million, nine hundred forty thousand, one hundred fifty-seven".