21290951 has 4 divisors (see below), whose sum is σ = 23226504. Its totient is φ = 19355400.

The previous prime is 21290933. The next prime is 21290999. The reversal of 21290951 is 15909212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21290951 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 (21290921) 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, 967760 + ... + 967781.

It is an arithmetic number, because the mean of its divisors is an integer number (5806626).

Almost surely, 2^21290951 is an apocalyptic number.

21290951 is a deficient number, since it is larger than the sum of its proper divisors (1935553).

21290951 is a wasteful number, since it uses less digits than its factorization.

21290951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1935552.

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 21290951 is about 4614.2118503597. The cubic root of 21290951 is about 277.1607238000.

The spelling of 21290951 in words is "twenty-one million, two hundred ninety thousand, nine hundred fifty-one".