21415297 has 4 divisors (see below), whose sum is σ = 21430720. Its totient is φ = 21399876.

The previous prime is 21415249. The next prime is 21415307. The reversal of 21415297 is 79251412.

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 4-Lehmer number, since φ(21415297) divides (21415297-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 21415297 - 2¹⁹ = 20891009 is a prime.

It is a super-2 number, since 2×21415297² = 917229891196418, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21415217) 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, 5397 + ... + 8482.

It is an arithmetic number, because the mean of its divisors is an integer number (5357680).

Almost surely, 2^21415297 is an apocalyptic number.

It is an amenable number.

21415297 is a deficient number, since it is larger than the sum of its proper divisors (15423).

21415297 is a wasteful number, since it uses less digits than its factorization.

21415297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15422.

The product of its digits is 5040, while the sum is 31.

The square root of 21415297 is about 4627.6664745852. Note that the first 3 decimals coincide. The cubic root of 21415297 is about 277.6992460252.

It can be divided in two parts, 21415 and 297, that added together give a palindrome (21712).

The spelling of 21415297 in words is "twenty-one million, four hundred fifteen thousand, two hundred ninety-seven".