20996551 has 8 divisors (see below), whose sum is σ = 22251600. Its totient is φ = 19776960.

The previous prime is 20996531. The next prime is 20996557. The reversal of 20996551 is 15569902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20996551 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20996551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20996557) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7641 + ... + 10018.

It is an arithmetic number, because the mean of its divisors is an integer number (2781450).

Almost surely, 2^20996551 is an apocalyptic number.

20996551 is a deficient number, since it is larger than the sum of its proper divisors (1255049).

20996551 is a wasteful number, since it uses less digits than its factorization.

20996551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17729.

The product of its (nonzero) digits is 24300, while the sum is 37.

The square root of 20996551 is about 4582.1993627515. The cubic root of 20996551 is about 275.8773127961.

The spelling of 20996551 in words is "twenty million, nine hundred ninety-six thousand, five hundred fifty-one".