21229157 has 4 divisors (see below), whose sum is σ = 21802956. Its totient is φ = 20655360.

The previous prime is 21229147. The next prime is 21229163. The reversal of 21229157 is 75192212.

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 8491396 + 12737761 = 2914^2 + 3569^2 .

It is a cyclic number.

It is not a de Polignac number, because 21229157 - 2⁸ = 21228901 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 (21229147) 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, 286844 + ... + 286917.

It is an arithmetic number, because the mean of its divisors is an integer number (5450739).

Almost surely, 2^21229157 is an apocalyptic number.

It is an amenable number.

21229157 is a deficient number, since it is larger than the sum of its proper divisors (573799).

21229157 is an equidigital number, since it uses as much as digits as its factorization.

21229157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 573798.

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

The square root of 21229157 is about 4607.5109332480. The cubic root of 21229157 is about 276.8923239215.

The spelling of 21229157 in words is "twenty-one million, two hundred twenty-nine thousand, one hundred fifty-seven".